1. Field of the Invention
The present invention relates to a brake control apparatus for controlling a brake mechanism of a vehicle and, more particularly, to a brake control apparatus that improves safety when a tire is punctured or the pressure thereof is reduced rapidly.
2. Discussion of the Related Art
It is important to improve safety during operation of a vehicle. A tire deflation detection method was disclosed in Japanese Patent Laid-Open No. 4-262907. In this document, puncture of a tire is detected and the driver is notified of such puncture by an alarm.
In the above disclosure, a technique was described in which angular-velocity signals supplied from wheel speed sensors attached to the respective wheels are subjected to a comparison. That is, the radii of gyration of the tires attached to the wheels are compared with one another. This allows a detection of the reduction in the pressure and also a display of the state of reduction of the tire pressure for the purpose of notifying the driver.
The above-mentioned system for detecting the pressure reduction of the tire for issuing an alarm to a driver is effective when the driver of the vehicle does not realize the pressure reduction (puncture) in the tire, and the pressure in the tire is reduced relatively moderately.
However, if the tire bursts or the pressure is reduced rapidly, the steering wheel will be instantaneously and uncontrollably turned in the direction of the punctured tire. Therefore, the alarm indicating the puncture of the tire is insufficient to prevent an accident due to delays in the operation of the steering wheel and the brake unit. The above-mentioned rapid change or turning of the steering wheel is especially apparent when either one of the front wheels has been punctured.